Loans and Leases (Details 9) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Purchased Credit Impaired Loans Composition [Line Items]
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 68,000	$ 0	$ 96,900
Loans held for investment, net	16,972,743,000	15,455,954,000
Loans and Leases Receivable, Allowance	(139,456,000)	(157,238,000)
Purchased Credit Impaired Loans and Leases [Member]
Purchased Credit Impaired Loans Composition [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	80,229,000	134,273,000
Loan Discounts	(22,193,000)	(25,849,000)
Loans held for investment, net	58,036,000	108,424,000
Loans and Leases Receivable, Allowance	(6,444,000)	(13,483,000)
Loans and Leases Receivable, Net Reported Amount, Covered	51,592,000	94,941,000
Mortgages [Member] | Purchased Credit Impaired Loans and Leases [Member]
Purchased Credit Impaired Loans Composition [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	72,399,000	112,982,000
Real Estate Construction [Member] | Purchased Credit Impaired Loans and Leases [Member]
Purchased Credit Impaired Loans Composition [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	0	1,901,000
Commercial Portfolio Segment [Member] | Purchased Credit Impaired Loans and Leases [Member]
Purchased Credit Impaired Loans Composition [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	7,568,000	19,109,000
Consumer Portfolio Segment [Member] | Purchased Credit Impaired Loans and Leases [Member]
Purchased Credit Impaired Loans Composition [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	$ 262,000	$ 281,000